The present invention relates to a solenoid assembly for driving an actuator in response to energization of electric coils.
Prior solenoid assemblies have plunger cores mounted in position on a shaft by E-rings. Due to dimensional errors, however, the plunger cores tend to wobble and produce noise, and the E-rings may not be mounted in place. A permanent magnet incorporated in the solenoid assembly may be defective as it is difficult to machine with desired dimensional accuracy. Swaging the plunger cores on the shaft is liable to damage the permanent magnet under compressive forces, and tedious and time-consuming. Yoke end members, coil bobbins, a central plate, and a main yoke are assembled together by swaging the main yoke on the yoke end members. However, the swaging process results in widely different dimensional errors of fabricated solenoid assemblies. The coil bobbins should be of an increased thickness to withstand swaging forces acting thereon, but the thick coil bobbins would render the solenoid assembly larger in diameter.